Slip of the Tongue
by realnikkiheat
Summary: He can't resist leaning into her from behind, speaking directly into her ear, "Now are we undercover?"


(A sequel of sorts to _Flick of the Wrist_, if you want to look at it that way.)

* * *

Castle can barely hear himself think as he stumbles across the crowded dance floor. The music is blasting so loud he can feel it down to his bones, the heavy bass causing his body to vibrate with every beat. The flashing lights in the club are about to give him a serious headache, and everywhere he turns he's overwhelmed by the stench of booze and sweat- honestly, it's a literal assault on his senses.

Ugh. He is _so_ old.

It's hard to feel too bad about himself, though, as he catches up to his girlfriend. His hot, younger, cop girlfriend who has taken him on a super cool undercover assignment. His girlfriend who has worn a very slinky red dress for their super cool assignment.

Rick lets his eyes slide over Beckett's body as he follows her- the thick, curly hair that flows down her back; the deep, red fabric that hangs across her shoulders, only to tighten at her hips, stretching across her backside. He can't help but let his eyes linger. It's not unlike the last time they had to stakeout a seedy club to find a drug dealer, except these days, he's free to do more than just look. A small surge of caveman-like pride shoots through him- he could trace those curves in his sleep now, knows the feel of them, the taste of them-

"Castle."

His eyes dart up to her face as she shouts his name over the music. Beckett's stopped moving to look at him over her shoulder, one eyebrow raised expectantly.

"How can you keep your eyes open for Savino when they're glued to my ass?"

He tries to look chagrined, he really does, but he can see the amusement behind her half-hearted glare. Whatever expression he comes up with must be charming enough, because she only rolls her eyes, reaching back to tangle her fingers with his as she leads him toward the bar.

They situate themselves in a dimly lit corner, Kate perched on a stool while he stands beside her, leaning against the counter as she fills him in on the case.

"So we think Savino might have known the victim?" It's a bit quieter here, but he still has to lean into her and shout over the music.

"We _know_ Savino _knew_ Winters," Beckett leans back against the bar, eyes scanning the room as she speaks. "We _think_ Savino might have been _dealing_ to Winters."

"Because the roommate thought Winters was on drugs?"

"Because the _girlfriend_ thought he might have been on drugs," she sighs. "Said Jeremy had been acting strange ever since he started hanging around Savino."

"And what did the roommate think?" Castle finally catches the bartender's eye over Beckett's shoulder, signaling for two beers.

"The roommate didn't think anything," she huffs, clearly losing patience as she shifts in her seat. "Said he hadn't noticed any change in Jeremy's behavior. Seriously, Castle, I'm trying to pay attention, here-"

"Excuse me," he bristles, sliding a bill across the bar and handing Beckett her bottle before grabbing his own. "I'm, just trying to get up to speed-"

"Well that's what happens when you decide you'd rather spend the afternoon driving around with Ryan than hanging out at the precinct with me. You fall behind."

"Well, we hadn't found a lead all morning!" He defends, his voice a little shrill- he _knew_ she was mad about that.

"Sorry my work isn't exciting enough for you anymore," she shrugs, still pointedly not looking at him as her eyes shift to the couches in the back corner of the club.

"Nonsense, Detective," he straightens and crowds against her, eager to charm his way back to her good side. The view of her cleavage- creamy skin peeking out from beneath layers of burgundy fabric- is an added bonus. "I find our undercover adventures plenty exciting."

"We are _not_ undercover," she reminds him, lifting her drink to her mouth and taking what he knows to be an expertly faked sip.

"_Beckett_," he whines, pouting at the top of her head. She knows he hates it when she ruins his super-spy fantasies.

"We don't have any backup," she continues, the hint of a laugh creeping into her voice. "We're just here to see if Savino is actually dealing. If he is, we'll come back another night with a team and arrest him."

"But we've taken down drug dealers before all by ourselves!"

"_I've_ taken down dealers by myself-"

"I handed you the cuffs!"

"And that was different," she points out. "We had more information then. We don't know how many guys Savino might have, how hard it is to get near him… And even if he is dealing, we still need to solidify our case against him for Winters' murder. You heard Gates. This is a fact-finding mission."

"Fine," he huffs, leans into her some more until her side is pressed into his chest. "I'll behave for our stupid, boring mission."

"Good," Beckett inhales deeply, leaning back and propping her elbows on the bar behind her. Castle can hear the smirk in her voice, even as he's distracted once again by the swell of her chest. "Then stop staring down my dress and start finding some facts, partner."

A half-hour later, they're still at the bar, making small talk while Castle slowly nurses both their drinks. He's been making a game of trying to distract her from her steady surveillance of the room- whispering in her ear, running his hand over her knee, brushing his fingers up and down her arm while they chat.

"Don't think I don't know what you're doing," her voice is low as she calls him out, finally sliding her eyes up to meet his.

"I have no idea what you're talking about." Castle can't keep the grin off his face, leaning heavily into her side. He can feel the warmth of her against his chest, see the pretty flush creeping up her neck; he feels the answering tug of want rumble through his body.

"It's not going to work," Beckett's voice is light and teasing as she relaxes into him.

"Still, this is nice," Castle confesses, lifting one hand to gently brush aside her hair, exposing the graceful column of her neck. She's returned her gaze to the club, looking for their mark, and he uses the opportunity to watch her, take in the elegant lines of her profile. "Almost like a _real_ date."

"What, Castle?" There's a smirk on her face, red lips pulled up into a coy smile. "You don't like the places I take you?"

He opens his mouth to respond, when he notices her tensing; the subtle shift of her body against his lets him know something is finally happening.

"Is he here?" Castle doesn't look around, instead leaning in to breathe his question against Beckett's ear. Just another guy at a bar trying to seduce a pretty girl.

"Eleven o'clock," Beckett tips her drink to her mouth as she answers, "on the couches in the back. Scrawny guy in the blue suit."

Castle slowly slides his eyes to the left, taking in the group of young men at the back of the club. Savino himself is not what he expected- skinny, with blond hair and a young face. Almost gangly. He's got a couple of big guys with him, though. He appears to be holding court, perching himself on the edge of a white leather couch and making eyes at a nearby group of women while his friends take in the room.

"Well, they certainly don't look like a study group," Castle observes inanely, turning back to Becket and leaning over her as he sips his beer.

"Jeremy's girlfriend sure didn't trust them. Said Savino runs with a pretty rough crowd." Kate shifts even closer to him, leaning in casually as she watches the group. "If we can just get evidence that he's dealing, then we can look into him some more and tie him to-"

Suddenly Kate shoots up off her stool, knocking her head against the underside of his chin. Castle groans, squeezing his eyes closed as his teeth rattle. When he opens them again, Kate is leaning against the bar, her back to the room and her head down.

"What the hell, Beckett?" He rubs the underside of his jaw. He's lucky he didn't bite off his tongue…

"That's Dennis Payton," she doesn't turn toward him as she speaks, and Castle has to lean in to catch her words.

"Who?" He turns his head quickly to Savino and his buddies, sees that another young man has joined them.

"The roommate," she sighs.

"Jeremy's roommate?" There's still a ringing in Castle's ears, but he's starting to catch up and this doesn't look good.

"Yes."

"The roommate you talked to this morning?"

"_Yes_," Kate hisses.

Definitely not good.

"What are they doing?" Beckett speaks to him from the side of her mouth, staring straight ahead across the club.

"Uh…" Castle flounders for a moment, trying to find a good position from which to watch them. He finally moves himself to Beckett's other side, propping himself against the bar and watching them over her shoulders. "Well, just the usual fist bump thing, I guess?"

"Does it look like he's dealing to Payton?"

"No, they're just talking," Castle observes the two young men, both standing now as they greet each other. "They definitely know each other, though."

"So Payton was obviously lying when he said he hadn't noticed any change in Jeremy."

Castle flicks his eyes down to Beckett, sees her chewing her lip as she thinks aloud.

"He was probably the one who introduced him to Savino," he offers. "And then if things went south between Savino and Winters…"

"Savino could have called in Payton to clean up the mess he'd made," Beckett finishes, glancing up to Castle. Her eyes are alight with the thrill of piecing together a case.

He shifts his gaze back to Savino, only to see that the group is now making their way out of the lounge and into the main area of the club.

"Whoa, Beckett," he straightens, hopes he's not being too obvious as he follows the men with his eyes, "I think they're on the move."

"Are they coming over here?" She stiffens, and Castle can feel the tension rolling off of her.

"Uh…I don't think so?" He squints, trying not to lose Savino in the crowd. "I'm not sure where they're going…"

"We have to get out of here," Beckett straightens, turning into his chest as she speaks. "We're in big trouble if Payton recognizes me."

"Um, okay," Castle flounders, eager to get Kate out of the building before things can take a turn for the worse. "Want me to see if we can avoid them? Maybe we can get to the entrance if we take the long way around the dance floor-"

"No," she cuts him off, all business as she assesses the situation. "There's a back entrance on the other side of the bar. We'll sneak out that way and leave through the alley."

Beckett weaves her fingers through his, and Castle lets her tug him away from the counter, making their way to the other side of the bar. He can't help the excitement bubbling up in him- the stakes are higher now, and his detective is dragging him through a seedy club, improvising an escape to avoid being made. _This_ is more what he had in mind for tonight.

He can't resist leaning into her from behind, speaking directly into her ear, "_Now_ are we undercover?"

Beckett only huffs, tightening her hold on his hand as she leads them toward safety.

* * *

The two of them spill out into a long, dark alleyway; a few crates and dented metal garbage cans litter the scene, and a tall, chain-link fence to their right covers the gap between the nightclub and the next building.

"Come on," Beckett tugs him sharply to the left, gripping his hand tightly as she leads him toward the street-

And their suspects, who appear from around the corner. The two young men seem to be engrossed in a discussion, Savino's lackeys flanking them; all four are unknowingly wandering straight toward Castle and Beckett.

Beckett spins around, her hair whipping him in the face as she pushes him backwards. Before Castle can figure out what's happening, she's got him backed up against a cold brick wall, body pressed against his and lips glued to his neck.

"Beckett?" He whispers, out of breath; his hands move to grab her instinctively, one resting on her hip, the other cradling the back of her head.

"Shh," she breathes against him, sending a shiver down his spine. "What are they doing?"

Castle forces his eyes to focus on the group of men at the end of the alley- an impressive feat considering his girlfriend is nibbling her way up his jaw and he's just realized he cannot feel any underwear beneath her dress. The four men have stopped a good distance away, too far for Castle to make out what they're saying. Savino and Payton look tense, deep in conversation, while the muscle hangs back a bit.

"Just talking, I think," Castle dips his head down, breathing the words directly into her ear. "I can't hear. They look angry."

He cranes his neck awkwardly, trying not to be too obvious as he checks out their suspects, only to see one of Savino's large friends watching them curiously. Castle quickly returns his attention to Beckett, pulling her closer with the hand on her waist and rolling his hips against hers as he kisses along her neck.

"We may have trouble."

"Not exactly an option, Castle." The words are barely audible even to him, little more than a warm, wet breath against his ear. He jumps a little when he feels Beckett's tongue dart out to play with his earlobe, "What's happening?"

He risks another glance to the left in time to catch one of the goons slowly making his way towards them, a suspicious scowl on his face.

Castle sinks his teeth into Beckett's shoulder, running one hand over the smooth curve of her behind; he fists the other hand in her hair, holding her still as his lips make their way back up to her ear.

"We've got company, Beckett." He can feel his heart thundering in his chest, a strange, heady combination of fear and arousal.

Suddenly, Beckett's lips are on his, hard and insistent. His head slams back into the wall, rough brick scraping against the back of his skull as her tongue forces its way into his mouth. He barely has a chance to respond before she's pulling away with a loud smack, leaving him in a cold state of shock.

And then his mind really goes blank, because Beckett is dropping to her knees, dark eyes staring up at him through her mussed hair, clever fingers making quick work of his belt buckle.

Castle's overwhelmed with arousal and distress and his fight or flight instinct is saying _get Kate out of here_ and some weird chivalrous part of him is concerned about her virtue because there are definitely four skeezy college kids who are about to see what only he gets to see and _is she serious?_

She is definitely serious.

Beckett reaches into his pants, her hot hand wrapping around his length and stroking once, twice before she finally releases him from his slacks. There's a moment of uncomfortable coolness before he's engulfed in the slick, familiar heat of her mouth. Castle can't help the grunt that escapes him, clenching his eyes shut and leaning his head back against the wall as her tongue circles the head of his shaft. She's got one hand fisted around the base of him, pumping slowly in time with her mouth; Castle can feel himself growing ever harder under her lips, aroused almost to the point of discomfort as his brain short-circuits.

The feeling of Beckett's nails digging into his thigh brings him back momentarily; his eyes pop open as he snaps his head downward to find Kate glaring up at him.

She pulls back, letting him slip out of her with a lewd, wet sound. She removes her hand from his leg and wraps it around the tip of his shaft, working him over with both hands as she pants, "_Watch_."

Castle can only nod, resisting the urge to whine or thrust his hips or _something _because God, he loves it when she gets bossy. He obediently glues his eyes to her, watches as she opens her mouth wide to take him in, only to glance back up and pull away at the last second.

"Watch _them_," she hisses, rolling her eyes and jerking her head toward their suspects.

Oh. Right.

He grunts as she takes him in again, and then forces himself to focus, leaning back against the wall and subtly turning his head to the left. Out of the corner of his eye, he sees that Savino's man has stopped in the middle of the alley, watching them with one eyebrow raised, almost amused. He turns back to his friends, nodding in their direction; Payton and the other thug chuckle, leering at them while Savino looks annoyed. No one make another move toward them, though.

Castle returns his gaze to Beckett, catching her eye and nodding once. She hums against him, red lips pursed obscenely around his length, and quickens her pace. She's staring up at him through eyes hooded with want, cheeks concaved as she sucks, and Castle can't help the thrust of his hips this time because-

Being watched while Beckett goes down on him doesn't really do it for him, but it's definitely doing something for Beckett, and _that_ is doing it for him. She takes him in farther; she has almost all of him now, trapped in the tight, wet confines of her mouth. Castle can feel his release pooling low in his belly, bubbling up within him when he's distracted by more movement to his left.

Their suspects are turning to leave, slowly making their way back out onto the street; Savino casts one last glance at them, rolling his eyes and looking irritated, and then they disappear around the corner.

"We're clear," Castle gasps as soon as they're gone. Beckett immediately pulls away, and he lets out a rather unmanly whimper at the loss of her mouth.

"Did they deal?" She breathes up at him, scraping her hair back with one hand.

"Are you serious?" He laughs almost hysterically, mirroring her movement as he runs his fingers through his own hair. "I have no idea!" She widens her eyes up at him, looking at once exasperated and insistent and this is such a ridiculous conversation to have while he's _exposed_ in a cold alley and she's staring up at him from her knees but _okay_.

"Uh," he inhales deeply, trying to focus. "I don't think so? Savino didn't look happy when they left. I think maybe we rained on their parade?"

"Okay," she nods, still panting as she talks to herself, "that's okay. We know that Payton has ties with Savino _and_ he lied to us. That changes things."

"That was close," he sighs, feeling his heart rate start to slow. "I was worried they might recognize me."

"Seriously, Castle?" She scowls up at him, unimpressed.

"What? Just because they're drug dealers, doesn't mean they don't read!"

She rolls her eyes, bracing herself with one hand on his forearm and rising to her feet, graceful as ever despite the grimace on her face. "We should get back to the station, fill the boys in."

The indignant squeak is out of Castle's mouth before he can help it. She only quirks an eyebrow, staring him down with a smirk and he _really_ doesn't want to whine, but-

"_Seriously, Beckett_?"

"It would serve you right," she snaps back instantly, sending him a heated glare as she crowds him against the wall.

"You're still mad about that?" He half-shouts, incredulous.

"I had to spend all night in the precinct-"

"That was months ago!"

"_Squirming_ in front of Gates-"

"It's a little different!" Castle gestures absurdly down to his erection, now half-hard in the cold air. "_You_ could at least hide your…situation."

She's trying to stare him down, he can tell, but her face is still flushed, chest heaving with the heavy panting that gives her away. He switches gears, sliding one hand around her hip and slowly pulling her against him.

"Besides, I think we both know you'd only be hurting yourself if you walked away now." His hand is slowly sliding up her thigh. "You're trying to tell me you're not wet from your little show?" He breathes the words against her, transfixed by the lipstick smudged across her mouth. Castle watches her closely, feeling himself grow hard again as her hips roll against his and she tugs her bottom lip between her teeth.

He can see the conflict playing across her face- would it be worth denying them both to punish him, or should she take what she wants? Castle doesn't break eye contact, silently daring her as his hand slides further up her leg to palm her bare ass. He knows he's won when Beckett dives in to claim him lips, digging her nails into the skin of his neck as she holds him in place.

She moans against him, a soft humming sound, as her hips meet his once more. Castle can feel her hands sliding down to his shoulders, and suddenly she's spinning them; when he pulls back to open his eyes, Beckett has her back against the wall, holding him to her tightly.

"You're doing the heavy lifting," she orders, breathless, as she hoists one long leg up around his waist. "I think I saw a rat down there."

Castle can't help the laugh that bursts out of him, even as he wraps his hands around her hips and hoists her into his arms. She slides up the brick wall with a huff, legs clenched tightly around him as her own soft chuckle escapes.

They're still laughing as Castle steadies her with one arm under her backside, the other hand slowly inching its way up her ribs. He feels her fingers tangling in his hair as he leans into her lips, their laughter mingling in the small space between them.

He kisses her hard, pressing her against the wall and breathing his words against her smile, "You always take me to the nicest places."


End file.
